Memory module in a package

ABSTRACT

A microelectronic package can include a substrate having first and second opposed surfaces, at least two pairs of microelectronic elements, and a plurality of terminals exposed at the second surface. Each pair of microelectronic elements can include an upper microelectronic element and a lower microelectronic element. The pairs of microelectronic elements can be fully spaced apart from one another in a horizontal direction parallel to the first surface of the substrate. Each lower microelectronic element can have a front surface facing the first surface of the substrate and a plurality of contacts at the front surface. A surface of each of the upper microelectronic elements can at least partially overlie a rear surface of the lower microelectronic element in its pair. The microelectronic package can also include electrical connections extending from at least some of the contacts of each lower microelectronic element to at least some of the terminals.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/346,185 filed Jan. 9, 2012, which claims the benefit of thefiling date of U.S. Provisional Patent Application No. 61/506,889 filedJul. 12, 2011, and U.S. Provisional Patent Application Nos. 61/542,488,61/542,495, and 61/542,553, all filed Oct. 3, 2011, the disclosures ofwhich are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

The subject matter of the present application relates to microelectronicpackages and assemblies incorporating microelectronic packages.

Semiconductor chips are commonly provided as individual, prepackagedunits. A standard chip has a flat, rectangular body with a large frontface having contacts connected to the internal circuitry of the chip.Each individual chip typically is contained in a package having externalterminals connected to the contacts of the chip. In turn, the terminals,i.e., the external connection points of the package, are configured toelectrically connect to a circuit panel, such as a printed circuitboard. In many conventional designs, the chip package occupies an areaof the circuit panel considerably larger than the area of the chipitself. As used in this disclosure with reference to a flat chip havinga front face, the “area of the chip” should be understood as referringto the area of the front face.

In “flip chip” designs, the front face of the chip confronts the face ofa package dielectric element, i.e., substrate of the package, and thecontacts on the chip are bonded directly to contacts on the face of thesubstrate by solder bumps or other connecting elements. In turn, thesubstrate can be bonded to a circuit panel through the externalterminals that overlie the substrate. The “flip chip” design provides arelatively compact arrangement; each package occupies an area of thecircuit panel equal to or slightly larger than the area of the chip'sfront face, such as disclosed, for example, in certain embodiments ofcommonly-assigned U.S. Pat. Nos. 5,148,265; 5,148,266; and 5,679,977,the disclosures of which are incorporated herein by reference. Certaininnovative mounting techniques offer compactness approaching or equal tothat of conventional flip-chip bonding. Packages that can accommodate asingle chip in an area of the circuit panel equal to or slightly largerthan the area of the chip itself are commonly referred to as “chip-scalepackages.”

Size is a significant consideration in any physical arrangement ofchips. The demand for more compact physical arrangements of chips hasbecome even more intense with the rapid progress of portable electronicdevices. Merely by way of example, devices commonly referred to as“smart phones” integrate the functions of a cellular telephone withpowerful data processors, memory and ancillary devices such as globalpositioning system receivers, electronic cameras, and local area networkconnections along with high-resolution displays and associated imageprocessing chips. Such devices can provide capabilities such as fullinternet connectivity, entertainment including full-resolution video,navigation, electronic banking and more, all in a pocket-size device.Complex portable devices require packing numerous chips into a smallspace. Moreover, some of the chips have many input and outputconnections, commonly referred to as “I/Os.” These I/Os must beinterconnected with the I/Os of other chips. The components that formthe interconnections should not greatly increase the size of theassembly. Similar needs arise in other applications as, for example, indata servers such as those used in internet search engines whereincreased performance and size reduction are needed.

Semiconductor chips containing memory storage arrays, particularlydynamic random access memory chips (DRAMs) and flash memory chips arecommonly packaged in single-chip or multiple-chip packages andassemblies. Each package has many electrical connections for carryingsignals, power and ground between terminals and the chips therein. Theelectrical connections can include different kinds of conductors such ashorizontal conductors, e.g., traces, beam leads, etc., which extend in ahorizontal direction relative to a contact-bearing surface of a chip,vertical conductors such as vias, which extend in a vertical directionrelative to the surface of the chip, and wire bonds that extend in bothhorizontal and vertical directions relative to the surface of the chip.

The transmission of signals within packages to chips of multi-chippackages poses particular challenges, especially for signals common totwo or more chips in the package such as clock signals, and address andstrobe signals for memory chips. Within such multi-chip packages, thelengths of the connection paths between the terminals of the package andthe chips can vary. The different path lengths can cause the signals totake longer or shorter times to travel between the terminals and eachchip. Travel time of a signal from one point to another is called“propagation delay” and is a function of the conductor length, theconductor's structure, and other dielectric or conductive structure inclose proximity therewith.

Differences in the times at which two different signals reach aparticular location can also be called “skew”. The skew in the arrivaltimes of a particular signal at two or more locations is a result ofboth propagation delay and the times at which the particular signalstarts to travel towards the locations. Skew may or may not impactcircuit performance. Skew often has little impact on performance whenall signals in a synchronous group of signals are skewed together, inwhich case all signals needed for operation arrive together when needed.However, this is not the case when different signals of a group ofsynchronous signals needed for operation arrive at different times. Inthis case the skew impacts performance because the operation cannot beperformed unless all needed signals have arrived. The embodimentsdescribed herein can include features that minimize skew that aredisclosed in the copending U.S. Provisional Patent Application No.61/506,889 (TESSERA 3.8-664), the disclosure of which is incorporated byreference herein.

Conventional microelectronic packages can incorporate a microelectronicelement that is configured to predominantly provide memory storage arrayfunction, i.e., a microelectronic element that embodies a greater numberof active devices to provide memory storage array function than anyother function. The microelectronic element may be or include a DRAMchip, or a stacked electrically interconnected assembly of suchsemiconductor chips. Typically, all of the terminals of such package areplaced in sets of columns adjacent to one or more peripheral edges of apackage substrate to which the microelectronic element is mounted.

In light of the foregoing, certain improvements can be made tomulti-chip microelectronic packages and assemblies in order to improveelectrical performance. These attributes of the present invention can beachieved by the construction of the microelectronic packages andassemblies as described hereinafter.

BRIEF SUMMARY OF THE INVENTION

In accordance with an aspect of the invention, a microelectronic packagecan include a substrate having first and second opposed surfaces, atleast two pairs of microelectronic elements, each pair ofmicroelectronic elements including an upper microelectronic element anda lower microelectronic element, a plurality of terminals exposed at thesecond surface, and electrical connections extending from at least someof contacts of each lower microelectronic element to at least some ofthe terminals. The pairs of microelectronic elements can be fully spacedapart from one another in a horizontal direction parallel to the firstsurface of the substrate. Each lower microelectronic element can have afront surface facing the first surface of the substrate and a pluralityof contacts at the front surface. The front surfaces of the lowermicroelectronic elements can be arranged in a single plane parallel tothe first surface. A surface of each of the upper microelectronicelements can at least partially overlie a rear surface of the lowermicroelectronic element in its pair. The microelectronic elements cantogether be configured to predominantly provide memory storage arrayfunction. The terminals can be configured for connecting themicroelectronic package to at least one component external to themicroelectronic package.

In a particular embodiment, at least some of the plurality of contactsof the lower microelectronic element of first and second ones of thepairs of microelectronic elements can be arranged in a respective columnof contacts defining respective first and second axes. The first andsecond axes can be transverse to one another. In one example, the firstand second axes can be orthogonal to one another. In an exemplaryembodiment, at least some of the plurality of contacts of the lowermicroelectronic element of first and second ones of the pairs ofmicroelectronic elements can be arranged in a respective column ofcontacts defining respective first and second axes. The first and secondaxes can be parallel to one another. In a particular example, the atleast two pairs of microelectronic elements can include four pairs ofmicroelectronic elements.

In one embodiment, at least some of the plurality of contacts of each ofthe lower microelectronic elements can be arranged in a column ofcontacts defining respective first, second, third, and fourth axes. Thefirst and third axes can be parallel to one another. The second andfourth axes can be transverse to the first and third axes. In aparticular embodiment, the lower microelectronic element of at least oneof the pairs of the microelectronic elements can be a first lowermicroelectronic element disposed adjacent a second lower microelectronicelement. The front surface of the second lower microelectronic elementcan be arranged in the single plane parallel to the first surface. Theupper microelectronic element that at least partially overlies the firstlower microelectronic element can also at least partially overlie thesecond lower microelectronic element.

In an exemplary embodiment, the terminals can be arranged in an areaarray. The terminals can have exposed contact surfaces that are coplanarwith one another. In a particular example, the electrical connectionscan include flip-chip connections extending between contacts of each ofthe lower microelectronic elements and conductive bond pads exposed atthe first surface of the substrate. In one embodiment, each of the lowermicroelectronic elements can overlie at least one aperture extendingbetween the first and second surfaces of the substrate. The electricalconnections can include leads having at least portions aligned with theat least one aperture. In a particular embodiment, each of the uppermicroelectronic elements can overlie at least one aperture extendingbetween the first and second surfaces of the substrate. The electricalconnections can include leads having at least portions aligned with theat least one aperture.

In one example, at least some of the leads can include wire bondsextending through at least one of the apertures. In an exemplaryembodiment, all of the leads can be wire bonds extending through atleast one of the apertures. In one embodiment, at least some of theleads can include lead bonds. In a particular example, each uppermicroelectronic element can have a plurality of contacts exposed at thefront surface thereof and arranged in at least one column of contactsdisposed adjacent to an edge of the front surface. Each column ofcontacts can be disposed beyond an edge of the corresponding one of thelower microelectronic elements.

In a particular embodiment, the microelectronic package can include fourpairs of microelectronic elements. The contacts of each microelectronicelement can include eight data I/O contacts. Alternatively, the contactsof each microelectronic element can include nine data I/O contacts. Inone embodiment, the microelectronic package can include ninemicroelectronic elements. The contacts of each microelectronic elementcan include eight data I/O contacts. In an exemplary embodiment, themicroelectronic package can include two pairs of microelectronicelements. The contacts of each microelectronic element can include eightdata I/O contacts. Alternatively, the contacts of each microelectronicelement include sixteen data I/O contacts.

In one example, the microelectronic package can also include a bufferelement electrically connected to at least some of the terminals and oneor more of the microelectronic elements in the microelectronic package.The buffer element can be configured to regenerate at least one signalreceived at one or more of the terminals of the microelectronic package.In a particular embodiment, the buffer element can be mounted to thefirst surface of the substrate. In an exemplary embodiment, the bufferelement can be mounted to the second surface of the substrate. In oneembodiment, the at least one signal can include all of the addresssignals transferred to the microelectronic package. In a particularexample, the at least one signal can include all of the command signals,address signals, bank address signals, and clock signals transferred tothe microelectronic package, the command signals being write enable, rowaddress strobe, and column address strobe signals, and the clock signalsbeing sampling clocks used for sampling the address signals.

In an exemplary embodiment, the at least one signal can include all ofthe data signals received by the microelectronic package. In oneembodiment, the microelectronic package can also include a nonvolatilememory element mounted to the substrate and configured to storeidentifying information. The nonvolatile memory element can beelectrically connected to one or more of the microelectronic elements.In a particular example, the microelectronic package can also include atemperature sensor. In a particular embodiment, the microelectronicelement can also include a decoupling capacitor element mounted to thesubstrate. The decoupling capacitor element can be electricallyconnected to one or more of the microelectronic elements. In oneembodiment, the substrate can be an element consisting essentially of amaterial having a CTE in a plane of the substrate less than 12 ppm/° C.In a particular embodiment, the substrate can include a dielectricelement consisting essentially of a material having a CTE in a plane ofthe substrate less than 30 ppm/° C.

In one example, the microelectronic elements can be configured tofunction together as an addressable memory module. The microelectronicpackage can be configured to store part of data received in each of themicroelectronic elements. In one embodiment, the microelectronic packagecan be configured to function as a dual in-line memory module. In anexemplary embodiment, the microelectronic package can have the samecommand and signal interface and is configured to transfer the sameamount of data as a dual in-line memory module. In a particularembodiment, each of the microelectronic elements can be configured topredominantly provide memory storage array function. In one example,each of the microelectronic elements can include a dynamic random accessmemory (“DRAM”) integrated circuit chip. In a particular example, eachof the microelectronic elements can be functionally and mechanicallyequivalent to the other ones of the microelectronic elements.

In a particular embodiment, the second surface of the substrate can havea central region occupying a central portion thereof. At least some ofthe terminals can be first terminals disposed in the central region. Inone embodiment, the at least two pairs of microelectronic elements caninclude four pairs of microelectronic elements. Each pair ofmicroelectronic elements can at least partially overlie an apertureextending between the first and second surfaces of the substrate. Eachaperture can have a length defining respective first, second, third, andfourth axes. The first and third axes can be parallel to one another.The second and fourth axes can be transverse to the first and thirdaxes. The central region can be bounded by the first, second, third, andfourth axes.

In an exemplary embodiment, each said aperture can be an outer aperture.Each pair of microelectronic elements can at least partially overlie aninner aperture extending between the first and second surfaces of thesubstrate adjacent a corresponding one of the outer apertures. Eachinner aperture can have a length defining an axis that is closer to acentroid of the substrate than the axis defined by the length of thecorresponding one of the outer apertures. In one embodiment, the firstterminals can be configured to carry all of the address signalstransferred to the microelectronic package.

In a particular example, the first terminals can be configured to carryat least some of the command signals, address signals, bank addresssignals, and clock signals transferred to the microelectronic package,the command signals being write enable, row address strobe, and columnaddress strobe signals, and the clock signals being sampling clocks usedfor sampling the address signals. The first terminals can be shared byat least two of the microelectronic elements. In one example, the firstterminals can be shared by each of the microelectronic elements. In anexemplary embodiment, the microelectronic package can also include aheat spreader in thermal communication with at least one of themicroelectronic elements. In a particular embodiment, the heat spreadercan at least partially overlie a rear surface of each of the uppermicroelectronic elements. In one embodiment, the heat spreader can atleast partially overlie the rear surface of each of the lowermicroelectronic elements.

In accordance with an aspect of the invention, a microelectronicassembly can include a plurality of microelectronic packages asdescribed above. The microelectronic assembly can also include a circuitpanel having panel contacts. The terminals of the package can be bondedto the panel contacts. In one embodiment, the circuit panel can have acommon electrical interface for transport of signals to and from each ofthe microelectronic packages. In an exemplary embodiment, each of themicroelectronic packages can be configured to have the samefunctionality as a dual in-line memory module. In a particular example,the circuit panel can be a motherboard. In one example, the circuitpanel can be a module configured to be attached to a motherboard.

In a particular embodiment, the microelectronic assembly can alsoinclude a buffer element mounted to the circuit panel and electricallyconnected to at least some of the microelectronic packages. The bufferelement can be configured to regenerate at least one signal received atone or more of the terminals of the microelectronic packages. In oneexample, the at least one signal can include all of the command signals,address signals, bank address signals, and clock signals transferred tothe microelectronic assembly, the command signals being write enable,row address strobe, and column address strobe signals, and the clocksignals being sampling clocks used for sampling the address signals. Inan exemplary embodiment, the at least one signal can include all of thedata signals received by the microelectronic assembly.

In accordance with an aspect of the invention, a module can include aplurality of microelectronic assemblies as described above. Eachmicroelectronic assembly can be electrically coupled to a second circuitpanel for transport of signals to and from each of the microelectronicassemblies. Further aspects of the invention can provide systems thatincorporate microelectronic assemblies according to the foregoingaspects of the invention, composite chips according to the foregoingaspects of the invention, or both in conjunction with other electroniccomponents electrically connected thereto. For example, the system canbe disposed in and/or mounted to a single housing, which can be aportable housing. Systems according to preferred embodiments in thisaspect of the invention can be more compact than comparable conventionalsystems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagrammatic perspective view of a microelectronic packageaccording to an embodiment of the present invention.

FIG. 1B is a side sectional view of the microelectronic package of FIG.1A, taken along the line 1B-1B of FIG. 1A.

FIG. 1C is a bottom view of the microelectronic package of FIG. 1A,showing the location of the microelectronic elements.

FIG. 2A is a diagrammatic perspective view of a microelectronic packageaccording to another embodiment having microelectronic elementsflip-chip mounted to a substrate.

FIG. 2B is a side sectional view of the microelectronic package of FIG.2A, taken along the line 2B-2B of FIG. 2A.

FIGS. 2C and 2D are side sectional views of variations of themicroelectronic package of FIG. 2A, having one or more uppermicroelectronic elements at least partially overlying correspondinglower microelectronic elements.

FIGS. 3A-3D are top views of microelectronic packages having fourmicroelectronic elements according to further embodiments, showing thelocation of the bond windows and the central region.

FIGS. 4A and 4B are top views of microelectronic packages having threemicroelectronic elements according to still further embodiments, showingthe location of the bond windows and the central region.

FIG. 5A is a diagrammatic perspective view of a microelectronic packageaccording to yet another embodiment having stacked microelectronicelements.

FIG. 5B is a side sectional view of the microelectronic package of FIG.5A, taken along the line 5B-5B of FIG. 5A.

FIG. 5C is a bottom view of the microelectronic package of FIG. 5A,showing the location of the microelectronic elements.

FIG. 6A is a diagrammatic perspective view of a microelectronic packageaccording to yet another embodiment having stacked microelectronicelements.

FIG. 6B is a side sectional view of the microelectronic package of FIG.6A, taken along the line 6B-6B of FIG. 6A.

FIG. 6C is a bottom view of the microelectronic package of FIG. 6A,showing the location of the microelectronic elements.

FIG. 7 is a diagrammatic perspective view of a microelectronic packageaccording to still another embodiment having stacked microelectronicelements.

FIG. 8A is a diagrammatic perspective view of a microelectronic assemblyhaving a plurality microelectronic packages mounted to a circuit panel.

FIG. 8B is a bottom view of the microelectronic assembly of FIG. 8A.

FIG. 8C-8E are diagrammatic perspective views of microelectronicassemblies according to further embodiments having a pluralitymicroelectronic packages mounted to a circuit panel.

FIG. 9 is a schematic depiction of a system according to one embodimentincluding a plurality of modules.

DETAILED DESCRIPTION

Certain embodiments of the invention provide a package ormicroelectronic assembly in which a microelectronic element, e.g., asemiconductor chip, or stacked arrangement of semiconductor chips, isconfigured to predominantly provide a memory storage array function. Insuch microelectronic element, the number of active devices, e.g.,transistors, therein that are configured, i.e., constructed andinterconnected with other devices, to provide memory storage arrayfunction, is greater than the number of active devices that areconfigured to provide any other function. Thus, in one example, amicroelectronic element such as a DRAM chip may have memory storagearray function as its primary or sole function. Alternatively, inanother example, such microelectronic element may have mixed use and mayincorporate active devices configured to provide memory storage arrayfunction, and may also incorporate other active devices configured toprovide another function such as processor function, or signal processoror graphics processor function, among others. In this case, themicroelectronic element may still have a greater number of activedevices configured to provide the memory storage array function than anyother function of the microelectronic element.

Embodiments of the invention herein provide packages that have more thanone semiconductor chip, i.e., a microelectronic element therein. Amultiple chip package can reduce the amount of area or space required toconnect the chips therein to a circuit panel, e.g., printed wiring boardto which the package may be electrically and mechanically connectedthrough an array of terminals, such as a ball grid array, land gridarray or pin grid array, among others. Such connection space isparticularly limited in small or portable computing devices, e.g.,handheld devices such as “smartphones” or tablets that typically combinethe function of personal computers with wireless connectivity to thebroader world. Multi-chip packages can be particularly useful for makinglarge amounts of relatively inexpensive memory available to a system,such as advanced high performance dynamic random access memory (“DRAM”)chips, e.g., in DDR3 type DRAM chips and its follow-ons.

The amount of area of the circuit panel needed to connect the multi-chippackage thereto can be reduced by providing common terminals on thepackage through which at least some signals travel on their way to orfrom two or more chips within the package. However, doing so in a waythat supports high performance operation presents challenges. To avoidundesirable effects such as undesirable reflections of the signal due tounterminated stubs, the traces, vias, and other conductors on a circuitpanel that electrically connect the terminals at the exterior of thepackage with the global wiring on the circuit panel must not be toolong. Heat dissipation also presents a challenge for advanced chips,such that it is desirable for at least one of the large flat surfaces ofeach chip to be coupled to a heat spreader or be exposed to or inthermal communication with a flow or air within an installed system. Thepackages described below can help to further these goals.

FIGS. 1A-1C illustrate a particular type of microelectronic package 10according to an embodiment of the invention. As seen in FIGS. 1A-1C, themicroelectronic package 10 can include packaging structure, for example,a substrate 20 having first and second opposed surfaces 21 and 22. Insome cases, the substrate 20 can consist essentially of a materialhaving a low coefficient of thermal expansion (“CTE”) in a plane of thesubstrate (in a direction parallel to the first surface 21 of thesubstrate), i.e., a CTE of less than 12 parts per million per degreeCelsius (hereinafter, “ppm/° C.”), such as a semiconductor materiale.g., silicon, or a dielectric material such as ceramic material orsilicon dioxide, e.g., glass. Alternatively, the substrate 20 mayinclude a sheet-like substrate that can consist essentially of apolymeric material such as polyimide, epoxy, thermoplastic, thermosetplastic, or other suitable polymeric material or that includes orconsists essentially of composite polymeric-inorganic material such as aglass reinforced structure of BT resin (bismaleimide triazine) orepoxy-glass, such as FR-4, among others. In one example, such asubstrate 20 can consist essentially of a material having a CTE of lessthan 30 ppm/° C. in the plane of the substrate, i.e., in a directionalong its surface.

In FIGS. 1A-1C, the directions parallel to the first surface 21 of thesubstrate 20 are referred to herein as “horizontal” or “lateral”directions, whereas the directions perpendicular to the first surfaceare referred to herein as upward or downward directions and are alsoreferred to herein as the “vertical” directions. The directions referredto herein are in the frame of reference of the structures referred to.Thus, these directions may lie at any orientation to the normal “up” or“down” directions in a gravitational frame of reference.

A statement that one feature is disposed at a greater height “above asurface” than another feature means that the one feature is at a greaterdistance in the same orthogonal direction away from the surface than theother feature. Conversely, a statement that one feature is disposed at alesser height “above a surface” than another feature means that the onefeature is at a smaller distance in the same orthogonal direction awayfrom the surface than the other feature.

At least one aperture 26 can extend between the first and secondsurfaces 21, 22 of the substrate 20. As can be seen in FIG. 1A, thesubstrate 20 can have four apertures 26 extending therethrough. Thesubstrate 20 can have a plurality of terminals 25, e.g., conductivepads, lands, or conductive posts or pins thereon. Such terminals 25 canbe exposed at the second surface of the substrate 20. The terminals 25can function as endpoints for the connection of the microelectronicpackage 10 with corresponding electrically conductive elements of anexternal component such as a circuit panel, e.g., printed wiring board,flexible circuit panel, socket, other microelectronic assembly orpackage, interposer, or passive component assembly, among others (e.g.,the circuit panel shown in FIG. 8A). In one example, such a circuitpanel can be a motherboard or DIMM module board. In a particularembodiment, the terminals can be arranged in an area array such as aball-grid array (BGA) (including joining elements as described below), aland-grid array (LGA), or a pin-grid array (PGA), among others. In oneembodiment, the terminals 25 can be arranged along the periphery of thesecond surface 22 of the substrate 20.

In an exemplary embodiment, the terminals 25 can include substantiallyrigid posts made from an electrically conductive material such ascopper, copper alloy, gold, nickel, and the like. The terminals 25 canbe formed, for example, by plating an electrically conductive materialinto openings in a resist mask, or by forming posts made, for example,of copper, copper alloy, nickel, or combinations thereof. Such posts canbe formed, for example, by subtractively patterning a metal sheet orother metal structure into posts what extend away from the substrate 20as terminals for electrically interconnecting the microelectronicpackage 10 with an external component such as the circuit panel 860described below, for example. The terminals 25 can be substantiallyrigid posts having other configurations, as described for example inU.S. Pat. No. 6,177,636, the disclosure of which is hereby incorporatedherein by reference. In one example, the terminals 25 can have exposedcontact surfaces that are coplanar with one another.

The microelectronic package 10 can include joining elements 11 attachedto the terminals 25 for connection with an external component. Thejoining elements 11 can be, for example, masses of a bond metal such assolder, tin, indium, a eutectic composition or combination thereof, oranother joining material such as a conductive paste or a conductiveadhesive. In a particular embodiment, the joints between the terminals25 and contacts of an external component (e.g., the circuit panel 860shown in FIG. 8A) can include an electrically conductive matrix materialsuch as described in commonly owned U.S. patent application Ser. Nos.13/155,719 and 13/158,797, the disclosures of which are herebyincorporated by reference herein. In a particular embodiment, the jointscan have a similar structure or be formed in a manner as describedtherein.

As used in this disclosure, a statement that an electrically conductiveelement is “exposed at” a surface of a structure indicates that theelectrically conductive element is available for contact with atheoretical point moving in a direction perpendicular to the surfacetoward the surface from outside the structure. Thus, a terminal or otherconductive element which is exposed at a surface of a structure canproject from such surface; can be flush with such surface; or can berecessed relative to such surface and exposed through a hole ordepression in the structure.

The terminals 25 can include first terminals 25 a exposed in a centralregion 23 of the second surface 22 of the substrate 20 and secondterminals 25 b exposed in a peripheral region 28 of the second surfaceoutside the central region. The arrangement shown in FIGS. 1A-1C canprovide a compact arrangement of microelectronic elements 30 and arelatively expansive central region 23 without requiring amicroelectronic element to overlie any other microelectronic element.

The first terminals 25 a can be configured to carry all of the commandsignals, address signals, bank address signals, and clock signalstransferred to the microelectronic package 10 from an externalcomponent. For example, in a microelectronic element that includes adynamic memory storage array, e.g., for a dynamic random access memory(“DRAM”), the command signals are write enable, row address strobe, andcolumn address strobe signals used by a microelectronic element withinthe microelectronic package 10, when such microelectronic element is adynamic random access memory storage device. Other signals such as ODT(one die termination), chip select, clock enable, are not part of thecommand signals that need to be carried by the first terminals 25 a.

The clock signals can be sampling clocks used for sampling the addresssignals. At least some of the second terminals 25 b can be configured tocarry signals other than the command signals, address signals, and clocksignals that are carried by the first terminals 25 a. Signals orreference potentials such as chip select, reset, power supply voltages,e.g., Vdd, Vddq, and ground, e.g., Vss and Vssq, can be carried by thesecond terminals 25 b; none of these signals or reference potentialsneeds to be carried by the first terminals 25 a.

In a particular example, such as the example shown in FIG. 1C, thesecond terminals 25 b can be disposed in at least one column in eachperipheral region 28. In one embodiment, at least some of the secondterminals 25 b that are configured to carry signals other than thecommand signals, address signals, and clock signals can be exposed inthe central region 23 of the second surface 22 of the substrate 20.

The microelectronic package 10 can also include a plurality ofmicroelectronic elements 30 each having a front surface 31 facing thefirst surface 21 of the substrate 20. In one example, each of themicroelectronic elements 30 can be bare chips or microelectronic unitseach incorporating a memory storage element such as a dynamic randomaccess memory (“DRAM”) storage array or that is configured topredominantly function as a DRAM storage array (e.g., a DRAM integratedcircuit chip). As used herein, a “memory storage element” refers to amultiplicity of memory cells arranged in an array, together withcircuitry usable to store and retrieve data therefrom, such as fortransport of the data over an electrical interface. In a particularexample, the microelectronic package 10 can be included in a singlein-line memory module (“SIMM”) or a dual in-line memory module (“DIMM”).

In a particular example, a microelectronic element 30 that includes amemory storage element can have at least a memory storage arrayfunction, but the microelectronic element may not be a full-functionmemory chip. Such a microelectronic element may not have a bufferingfunction itself, but it may be electrically connected to othermicroelectronic elements in a stack of microelectronic elements, whereinat least one microelectronic element in the stack has a bufferingfunction (the buffering microelectronic element could be a buffer chip,a full-function memory chip, or a controller chip).

In other examples, one or more of the microelectronic elements in any ofthe packages described herein can embody a greater number of activedevices to provide memory storage array function than any otherfunction, e.g., as flash memory, DRAM or other type of memory, and canbe arranged in a package together with another microelectronic elementor “logic chip” that is configured to predominantly provide logicfunction. In a particular embodiment, the logic chip can be aprogrammable or processor element such as a microprocessor or othergeneral purpose computing element. The logic chip can be amicrocontroller element, graphics processor, floating point processor,co-processor, digital signal processor, etc. In a particular embodiment,the logic chip can predominantly perform hardware state machinefunctions, or otherwise be hard-coded to serve a particular function orpurpose. Alternatively, the logic chip can be an application specificintegrated circuit (“ASIC”) or field programmable gate array (“FPGA”)chip. In such variation, the package then may be a “system in a package”(“SIP”).

In another variation, a microelectronic element in any of the packagesdescribed herein can have both logic and memory function embeddedtherein, such as a programmable processor having one or more associatedmemory storage arrays embedded therewith in the same microelectronicelement. Such microelectronic element is sometimes referred to as a“system-on-a-chip” (“SOC”), in that logic such as a processor isembedded together with other circuitry such as a memory storage array orcircuitry for performing some other function that may be a specializedfunction.

In a particular example, each of the microelectronic elements 30 can befunctionally and mechanically equivalent to the other ones of themicroelectronic elements, such that each microelectronic element canhave the same pattern of electrically conductive contacts 35 at thefront surface 31 with the same function, although the particulardimensions of the length, width, and height of each microelectronicelement can be different than that of the other microelectronicelements.

Each microelectronic element 30 can have a plurality of electricallyconductive contacts 35 exposed at the front surface 31 thereof. Thecontacts 35 of each microelectronic element 30 can be arranged in one ormore columns disposed in a central region 36 of the front surface 31that occupies a central portion of an area of the front surface. Thecentral region 36, for example, may occupy an area of the front surface31 that includes a middle third of the shortest distance between opposedperipheral edges 32 a, 32 b of the microelectronic element 30. As shownin FIG. 1B, the contacts 35 of each microelectronic element 30 can bealigned with at least one of the apertures 26.

In a particular embodiment, the microelectronic package 10 can have fourmicroelectronic elements 30, the contacts 35 of each microelectronicelement including eight data I/O contacts. In another embodiment, themicroelectronic package 10 can have four microelectronic elements 30,the contacts 35 of each microelectronic element including sixteen dataI/O contacts. In a particular example, the microelectronic package 10(and any of the other microelectronic packages described herein) can beconfigured to transfer, i.e., receive by the package, or transmit fromthe package thirty-two data bits in parallel in a clock cycle. Inanother example, the microelectronic package 10 (and any of the othermicroelectronic packages described herein) can be configured to transfersixty-four data bits in parallel in a clock cycle. A number of otherdata transfer quantities are possible, among which only a few suchtransfer quantities will be mentioned without limitation. For example,the microelectronic package 10 (and any of the other microelectronicpackages described herein) can be configured to transfer seventy-twodata bits per clock cycle that can include a set of sixty-fourunderlying bits that represent data and eight bits that are errorcorrection code (“ECC”) bits for the sixty-four underlying bits.Ninety-six data bits, 108 bits (data and ECC bits), 128 data bits, and144 bits (data and ECC bits) are other examples of data transfer widthsper cycle that the microelectronic package 10 (and any of the othermicroelectronic packages described herein) can be configured to support.

In the embodiment of FIGS. 1A-1C, at least some signals that passthrough the first terminals 25 a of the package can be common to atleast two of the microelectronic elements 30. These signals can berouted through connections such as conductive traces extending in adirection parallel to the second surface 22 of the substrate 20 from thefirst terminals 25 a to the corresponding contacts 35 of themicroelectronic elements 30. The microelectronic package 10 can route asignal that is common to multiple microelectronic elements 30 through acommon first terminal 25 a of the package, rather than through two ormore terminals of the package each dedicated to a specific one of themicroelectronic elements. In this way, an amount of area of thesubstrate 20 occupied by such terminals 25 can be reduced.

FIG. 1A illustrates a particular arrangement of microelectronic elements30 a, 30 b, 30 c, and 30 d on a substrate 20 similar to the shape of apinwheel. In this case, at least some of the plurality of contacts 35 ofeach microelectronic element 30 can be arranged in a respective columnof contacts defining respective first, second, third, and fourth axis 29a, 29 b, 29 c, and 29 d (collectively axes 29). In the example shown inFIG. 1A, the first and third axes 29 a and 29 c can be parallel to oneanother, the second and fourth axes 29 b and 29 d can be parallel to oneanother, and the first and third axes can be transverse to the secondand fourth axes. In a particular embodiment, the first and third axes 29a and 29 c can be orthogonal to the second and fourth axes 29 b and 29d. In one example, each of the first, second, third and fourth axes 29a, 29 b, 29 c, and 29 d, can be defined by a length of a correspondingone of the apertures 26 a, 26 b, 26 c, and 26 d, so that the apertures26 can be arranged in a pinwheel configuration as described above.

In the particular example shown in FIG. 1A, the axis 29 of eachmicroelectronic element 30 can bisect the respective microelectronicelement and can intersect the area of exactly one other microelectronicelement in the microelectronic package 10. For example, the first axis29 a can bisect the first microelectronic element 30 a and can intersectthe area of exactly one other microelectronic element 30. Similarly, thesecond axis 29 b can bisect the second microelectronic element 30 b andcan intersect the area of exactly one other microelectronic element 30.The same is also true of the third axis 29 c which can bisect the thirdmicroelectronic element 30 c and can intersect the area of exactly oneother microelectronic element 30. Indeed, this is also true of thefourth axis 29 d that can bisect the fourth microelectronic element 30 dand can intersect the area of exactly one other microelectronic element30.

Electrical connections between the contacts 35 and the terminals 25 caninclude optional leads, e.g., wire bonds 40, or other possible structurein which at least portions of the leads are aligned with at least one ofthe apertures 26. For example, as seen in FIG. 1B, at least some of theelectrical connections can include a wire bond 40 that extends beyond anedge of an aperture 26 in the substrate, and is joined to the contact 35and a conductive element 24 of the substrate. In one embodiment, atleast some of the electrical connections can include lead bonds. Suchconnections can include leads that extend along either or both of thefirst and second surfaces 21, 22 of the substrate 20 between theconductive elements 24 and the terminals 25. In a particular example,such leads can be electrically connected between the contacts 35 of eachmicroelectronic element 30 and the terminals 25, each lead having aportion aligned with at least one of the apertures 26.

In one example, one or more additional chips 30′ can be mounted to thesubstrate 20 having a surface 31′ facing the first surface 21 (FIG. 1A)or the second surface 22 of the substrate 20. Such an additional chip30′ can be flip-chip bonded to electrically conductive contacts exposedat the first surface 21 of the substrate 20.

One or more of the additional chips 30′ can be a buffering chip that canbe configured to help provide signal isolation for each of themicroelectronic elements 30 with respect to components external to themicroelectronic package 10. In one example, such a buffering chip orbuffer element can be electrically connected to at least some of theterminals 25 and one or more of the microelectronic elements 30 in themicroelectronic package 10, the buffer element configured to regenerateat least one signal received at one or more of the terminals of themicroelectronic package 10. In one embodiment, wherein themicroelectronic package 10 is a registered DIMM, the at least one signalcan include all of the command signals, address signals, bank addresssignals, and clock signals transferred to the package, the commandsignals being write enable, row address strobe, and column addressstrobe signals, and the clock signals being sampling clocks used forsampling the address signals. In a particular example, when themicroelectronic package 10 is a load-reduced DIMM (“LRDIMM”), the atleast one signal can include all of the data signals received by themicroelectronic package.

In a particular embodiment, one or more of the additional chips 30′ canbe a decoupling capacitor. One or more decoupling capacitors can bedisposed between the microelectronic elements 30 instead of or inaddition to the aforementioned buffering chips. Such decouplingcapacitors can be electrically connected to internal power and groundbuses inside the microelectronic package 10.

In one embodiment, one of the additional chips 30′ can be a nonvolatilememory element such as an electrical erasable programmable read onlymemory (“EEPROM”) mounted to the substrate 20 and configured topermanently store identifying information of the microelectronic package10, such as the data width and depth of the microelectronic package.Such a nonvolatile memory element can be electrically connected to oneor more of the microelectronic elements 30.

In one example, one of the additional chips 30′ can be a temperaturesensor. Such a temperature sensor can be electrically connected to oneor more of the microelectronic elements 30. In one example, thetemperature sensor can include a diode and can be mounted to thesubstrate 20. In a particular embodiment, one of the additional chips30′ can be a serial presence detect element mounted to the substrate 20.

The microelectronic package 10 can further include an adhesive 12between the front surface 31 of the microelectronic elements 30 and thefirst surface 21 of the substrate 20. The microelectronic package 10 canalso include an encapsulant (not shown) that can optionally cover,partially cover, or leave uncovered the rear surfaces 32 of themicroelectronic elements 30. For example, in the package shown in FIGS.1A-1C, an encapsulant can be flowed, stenciled, screened or dispensedonto the rear surfaces 32 of the microelectronic elements 30. In anotherexample, the encapsulant can be a mold compound which is formed thereonby overmolding.

In variations of the embodiments described above it is possible for thecontacts of microelectronic elements to not be disposed in centralregions of the surfaces thereof. Rather, the contacts may be disposed inone or more rows adjacent an edge of such microelectronic element. Inanother variation, the contacts of a microelectronic element can bedisposed adjacent two opposed edges of such microelectronic element. Inyet another variation, the contacts of a microelectronic element can bedisposed adjacent any two edges, or be disposed adjacent more than twoedges of such microelectronic element. In such cases, locations ofapertures in the substrate can be modified to correspond to suchlocations of the contacts disposed adjacent such edge or edges of themicroelectronic element.

FIGS. 2A and 2B illustrate a variation of the embodiment described aboverelative to FIGS. 1A-1C, in which the microelectronic elements 230 areflip-chip bonded to the first surface 221 of the substrate 220. In suchan embodiment, electrical connections between the microelectronicelements 230 and the substrate 220 include flip-chip connectionsextending between contacts of each of the microelectronic elements andconductive bond pads exposed at the first surface 221 of the substrate.

FIG. 2C shows a variation of the embodiment described above relative toFIGS. 2A and 2B, in which one or more of the microelectronic elements230 is a lower microelectronic element 230′, and the microelectronicpackage 210′ includes upper microelectronic elements 230 a, 230 b, and230 c each having a surface at least partially overlying a rear surface232 of the lower microelectronic element. As shown in FIG. 2C, the uppermicroelectronic elements 230 a, 230 b, and 230 c are electricallyconnected with the lower microelectronic element 230′ through at leastone conductive via 209 extending through the lower microelectronicelement. In a particular embodiment, the lower microelectronic element230″ can be wire-bonded to conductive contacts exposed at the secondsurface 222 of the substrate 220.

FIG. 2D shows a variation of the embodiment described above relative toFIGS. 2A and 2B, in which one or more of the microelectronic elements230 is a lower microelectronic element 230″, and the microelectronicpackage 210″ includes upper microelectronic elements 230 a and 230 beach having a surface at least partially overlying a rear surface 232 ofthe lower microelectronic element. As shown in FIG. 2D, the uppermicroelectronic elements 230 a and 230 b are electrically connected withthe lower microelectronic element 230″ through wire bonds 240 extendingbetween contacts 235 of the upper microelectronic elements andconductive elements 245 exposed at the rear surface 232 of the lowermicroelectronic element 230″. In a particular embodiment, the lowermicroelectronic element 230″ can be wire-bonded to conductive contactsexposed at the second surface 222 of the substrate 220.

FIGS. 3A-3D show additional variations of the microelectronic package 10shown in FIGS. 1A-1C having different locations of the microelectronicelements relative to the first surface of the substrate. In FIGS. 3A-3D,the respective microelectronic packages 301, 302, 303, and 304 can eachinclude four microelectronic elements 330, each microelectronic elementhaving contacts that are wire-bonded through a respective aperture 326to conductive contacts exposed at the second surface of the substrate320. The apertures 326 can define portions of the boundary of a centralregion 323 of the second surface of the substrate, where shared firstterminals connected to at least two of the microelectronic elements 330can be located.

In FIG. 3A, the microelectronic package 301 has microelectronic elements330 arranged similarly to the microelectronic elements 30 of FIGS.1A-1C, but the microelectronic elements 330 each have a substantiallysquare shape, so there is very little space at the first surface of thesubstrate 320 located between the microelectronic elements.

In FIG. 3B, each of the microelectronic elements 330 has first andopposed edges 332 a and 332 b oriented parallel to a length of therespective aperture 326. The first edge 332 a of each of themicroelectronic elements 330 can define an axis 329 that does not extendthrough the areas of any of the other microelectronic elements. In suchan embodiment, there is a larger space at the first surface of thesubstrate 320 located between the microelectronic elements 330, and thecentral region 323 of the second surface of the substrate can berelatively large.

In FIG. 3C, each of the microelectronic elements 330 can overlie arespective aperture 326 that defines an axis 329 that does not extendthrough the areas of any of the other microelectronic elements. However,compared to FIG. 3B, two of the microelectronic elements 330 a and 330 chave been moved closer to a center of the first surface of the substrate320. Each of the microelectronic elements 330 has first and opposededges 332 a and 332 b oriented parallel to a length of the respectiveaperture 326. The first edge 332 a of the first and thirdmicroelectronic elements 330 a and 330 c can define respective axes 329a and 329 c that extend through the areas of the second and fourthmicroelectronic elements 330 b and 330 d.

FIG. 3D is a variation of FIG. 3C where two of the microelectronicelements 330 a and 330 c have been moved even closer to a center of thefirst surface of the substrate 320. The first and third microelectronicelements 330 a and 330 b can overlie a respective aperture 326 a and 326c that defines a respective axis 329 and 329′ that extends through theareas of the second and fourth microelectronic elements 330 b and 330 d.Also, each of the microelectronic elements 330 has first and opposededges 332 a and 332 b oriented parallel to a length of the respectiveaperture 326. The first edge 332 a of the first and thirdmicroelectronic elements 330 a and 330 c can define respective axes 329a and 329 c that also extend through the areas of the second and fourthmicroelectronic elements 330 b and 330 d.

FIGS. 4A and 4B show additional variations of the microelectronicpackage 10 shown in FIGS. 1A-1C having three microelectronic elementshaving front surfaces arranged in a single plane parallel to the firstsurface of the substrate 420. In FIG. 4A, the microelectronic package401 has three microelectronic elements 430 mounted to the first side ofthe substrate 410. A first one of the microelectronic elements 430 a canhave additional microelectronic elements at least partially overlyingand electrically connected with the first microelectronic element, forexample, in a manner such as that shown in FIG. 2C or FIG. 2D. A secondone of the microelectronic elements 430 b can be a controller, forexample. In FIG. 4B, the microelectronic package 402 is the same as themicroelectronic package 10 shown in FIGS. 1A-1C, except that one of themicroelectronic elements 430 in the pinwheel configuration is omitted,leaving three microelectronic elements having front surfaces arranged ina single plane parallel to the first surface of the substrate 420.

FIGS. 5A-5C illustrate a variation of the embodiment described aboverelative to FIGS. 1A-1C. The microelectronic package 510 is similar tothe microelectronic package 10 shown in FIGS. 1A-1C, except that in themicroelectronic package 510, the front surface 531 of an uppermicroelectronic element 530 b at least partially overlies a rear surface532 of each of the four lower microelectronic elements 530 a. The lowermicroelectronic elements 530 a and the upper microelectronic elements530 b can be arranged in pairs 507 of microelectronic elements. Adjacentpairs 507 of microelectronic elements, such as a first pair 507 a and asecond pair 507 b can be fully spaced apart from one another in ahorizontal direction H parallel to the first surface 521 of thesubstrate 520. In a particular example, the microelectronic elements 530a and 530 b can together embody a greater number of active devices toprovide memory storage array function than any other function.

In one embodiment, the microelectronic package 510 can have eightmicroelectronic elements 530 (including four lower microelectronicelements 530 a and four upper microelectronic elements 530 b), eachmicroelectronic element including eight data I/O contacts. In anotherembodiment, the microelectronic package 510 can have eightmicroelectronic elements 530 (including four lower microelectronicelements 530 a and four upper microelectronic elements 530 b), eachmicroelectronic element including nine data I/O contacts.

In a particular example, at least some of the electrically conductivecontacts 535 exposed at the front surface 531 of the lowermicroelectronic element 530 a of adjacent pairs of microelectronicelements can be arranged in respective columns of contacts definingfirst and second axes 529 a and 529 a′. As shown in FIG. 5A, such firstand second axes 529 a and 529 a′ can be transverse to one another. In aparticular example, the first and second axes 529 a and 529 a′ can beorthogonal to one another. In one embodiment, the first and second axes529 a and 529 a′ can be parallel to one another.

In one embodiment, each pair of microelectronic elements 507 can atleast partially overlie an outer aperture 526 a extending between thefirst and second surfaces 521, 522 of the substrate 520. Each outeraperture 526 a can have a length defining an outer axis 509 a. The fourouter axes 509 a can be arranged in a pinwheel configuration asdescribed above, wherein the outer axes 509 a can be arranged in twoparallel pairs of outer axes, each pair being transverse to the otherpair. A central region 523 occupying a central portion of the secondsurface 522 of the substrate 520 can be bounded by the four outer axes509 a, as shown in FIG. 5C. At least some of the terminals 525 exposedat in the central region 523 of the second surface 522 of the substrate520 can be first terminals having a function similar to the firstterminals 25 a described above.

In an exemplary embodiment, each pair of microelectronic elements 507can also at least partially overlie an inner aperture 526 b extendingbetween the first and second surfaces 521, 522 of the substrate 520adjacent a corresponding one of the outer apertures 526 a in the samepair of microelectronic elements, as shown in FIG. 5A. Each inneraperture 526 b can have a length defining an axis 509 b that is closerto a centroid 501 of the substrate than the axis 509 a defined by thelength of the corresponding one of the outer apertures 526 a.

As shown in FIG. 5A, each lower microelectronic element 530 a overliesan outer aperture 526 a, and each upper microelectronic element 530 boverlies an inner aperture 526 b. In a particular embodiment, each uppermicroelectronic element 530 b can overlie an outer aperture 526 a, andeach lower microelectronic element 530 a can overlie an inner aperture526 b. In one example, one or more of the lower microelectronic elements530 a can overlie corresponding outer apertures 526 a, and the otherlower microelectronic elements can overlie corresponding inner apertures526 b, while one or more of the upper microelectronic elements 530 b canoverlie corresponding outer apertures, and the other uppermicroelectronic elements can overlie corresponding inner apertures.

A spacer 514 can be positioned between the front surface 531 of theupper microelectronic elements 530 b and a portion of the first surface521 of the substrate 520, with or without an adhesive 512 locatedbetween the spacer and the first surface of the substrate. Such a spacer514 can be made, for example, from a dielectric material such as silicondioxide, a semiconductor material such as silicon, or one or more layersof adhesive. If the spacer 514 includes adhesives, the adhesives canconnect the upper microelectronic elements 530 b to the substrate 520.In one embodiment, the spacer 514 can have substantially the samethickness T1 in a vertical direction V substantially perpendicular tothe first surface 521 of the substrate 520 as the thickness T2 of thelower microelectronic elements 530 a between the front and rear surfaces531, 532 thereof. In a particular embodiment, for example, when thespacer 514 is made of an adhesive material, the spacer 514 can be usedwithout an adhesive 512 such as the adhesive 12 described above.

FIGS. 6A-6C illustrate a variation of the embodiment described aboverelative to FIGS. 5A-5C. The microelectronic package 610 is similar tothe microelectronic package 510 shown in FIGS. 5A-5C, except that in themicroelectronic package 610, the front surface 631 of an uppermicroelectronic element 630 b at least partially overlies a rear surface632 of two lower microelectronic elements 630 a. All of the lowermicroelectronic elements 630 a can have front surfaces 631 arranged in asingle plane parallel to the first surface 621 of the substrate 620.

FIG. 7 illustrates another variation of the embodiment described aboverelative to FIGS. 5A-5C. The microelectronic package 710 is the same asthe microelectronic package 510 shown in FIGS. 5A-5C, exceptmicroelectronic package 710 includes three pairs 707 of microelectronicelements, each pair having a lower microelectronic element 730 a and anupper microelectronic element 730 b. In place of a fourth pair 707 ofmicroelectronic elements, the microelectronic package 710 includes agrouping of two lower microelectronic elements 730 a and onecorresponding upper microelectronic element 730 b having a front surface731 at least partially overlying rear surfaces 732 of each of the uppermicroelectronic elements. In one example, the microelectronic package710 can have nine microelectronic elements 730 each including eight dataI/O contacts.

Referring now to FIGS. 8A and 8B, a microelectronic assembly 801 caninclude a plurality of microelectronic packages 810 that can be mountedto a common circuit panel 860. Each of the microelectronic packages 810is shown as a microelectronic package 10 from FIGS. 1A-1C, but suchmicroelectronic packages 810 can be any of the microelectronic packagesdescribed above with reference to FIGS. 1A through 7. The circuit panel860 can have first and second opposing surfaces 861 and 862 andpluralities of electrically conductive panel contacts exposed at therespective first and second surfaces. The microelectronic packages 810can be mounted to the panel contacts, for example, by the joiningelements 11 shown in FIG. 1B that can extend between the terminals ofeach microelectronic package and the panel contacts. As shown in FIG.8B, the second surface of the substrate of the a first microelectronicpackage 810 a and the second surface of the substrate of a secondmicroelectronic package 810 b can at least partially overlie oneanother. In a particular example, the circuit panel 860 can include anelement having a CTE less than 30 ppm/° C. In one embodiment, such anelement can consist essentially of semiconductor, glass, ceramic orliquid crystal polymer material.

In a particular embodiment, the circuit panel 860 can have a pluralityof parallel exposed edge contacts 850 adjacent an insertion edge 851 ofat least one of the first and second surfaces 861, 862 for mating withcorresponding contacts of a socket (shown in FIG. 9) when themicroelectronic assembly 801 is inserted in the socket. Some or all ofthe edge contacts 850 can be exposed at either or both of the first orsecond surfaces 861, 862 of the microelectronic assembly 801. In oneexample, the circuit panel 860 can be a motherboard. In an exemplaryembodiment, the circuit panel 860 can be a module such as a memorysubsystem that can be configured to be attached to another circuit panelsuch as a motherboard. Such attachment of the circuit panel 860 toanother circuit panel can be as described below.

The exposed edge contacts 850 and the insertion edge 851 can be sizedfor insertion into a corresponding socket (FIG. 9) of other connector ofa system, such as can be provided on a motherboard. Such exposed edgecontacts 850 can be suitable for mating with a plurality ofcorresponding spring contacts (FIG. 9) within such socket connector.Such spring contacts can be disposed on single or multiple sides of eachslot to mate with corresponding ones of the exposed edge contacts 850.In one example, at least some of the edge contacts 850 can be usable tocarry at least one of a signal or a reference potential between therespective edge contact and one or more of the microelectronic packages810. In a particular embodiment, the microelectronic assembly 801 canhave the same signal interface as a dual in-line memory module.

FIGS. 8C-8E show variations of the microelectronic assembly 801 shown inFIGS. 8A and 8B including microelectronic packages 810′ that are shownas the microelectronic package 510 from FIGS. 5A-5C. In FIG. 8C, themicroelectronic package 802 has five microelectronic packages 810′mounted to a first side 861 of the circuit panel 860.

In FIG. 8D, the microelectronic package 803 has five microelectronicpackages 810′ mounted to a first surface 861 of the circuit panel 860,and an additional chip 830′ such as the additional chip 30′ shown inFIG. 1A is shown having a surface facing the first surface of thecircuit panel. Such an additional chip 830′ can be any of the types ofadditional chips described above with reference to FIGS. 1A-1C,including, for example, a buffering chip that can be configured to helpprovide signal isolation for each of the microelectronic packages 810′with respect to components external to the microelectronic assembly 803.In one example, the additional chip 830′ can include a memorycontroller.

In FIG. 8E, the microelectronic package 804 has five microelectronicpackages 810′ each mounted to a respective socket 805, and each socketis mounted to the first surface 861 of the circuit panel 860.

The microelectronic packages and microelectronic assemblies describedabove with reference to FIGS. 1 through 8E can be utilized inconstruction of diverse electronic systems, such as the system 900 shownin FIG. 9. For example, the system 900 in accordance with a furtherembodiment of the invention includes a plurality of modules orcomponents 906 such as the microelectronic packages and microelectronicassemblies as described above in conjunction with other electroniccomponents 908 and 910.

The system 900 can include a plurality of sockets 905, each socketincluding a plurality of contacts 907 at one or both sides of thesocket, such that each socket 905 can be suitable for mating withcorresponding exposed edge contacts or exposed module contacts of acorresponding module or component 906. In the exemplary system 900shown, the system can include a circuit panel or motherboard 902 such asa flexible printed circuit board, and the circuit panel can includenumerous conductors 904, of which only one is depicted in FIG. 9,interconnecting the modules or components 906 with one another. Such acircuit panel 902 can transport signals to and from each of themicroelectronic packages 10 or 110 included in the system 900. However,this is merely exemplary; any suitable structure for making electricalconnections between the modules or components 906 can be used. In aparticular example, rather than having the modules or components 906coupled to the circuit panel 902 through sockets 905, one or more of themodules or components 906 such as the microelectronic package 10 can bemounted directly to the circuit panel 902.

In a particular embodiment, the system 900 can also include a processorsuch as the semiconductor chip 908, such that each module or component906 can be configured to transfer a number N of data bits in parallel ina clock cycle, and the processor can be configured to transfer a numberM of data bits in parallel in a clock cycle, M being greater than orequal to N.

In one example, the system 900 can include a processor chip 908 that isconfigured to transfer thirty-two data bits in parallel in a clockcycle, and the system can also include four modules 906 such as themodule 10 described with reference to FIGS. 1A through 1C, each module906 configured to transfer eight data bits in parallel in a clock cycle(i.e., each module 906 can include first and second microelectronicelements, each of the two microelectronic elements being configured totransfer four data bits in parallel in a clock cycle).

In another example, the system 900 can include a processor chip 908 thatis configured to transfer sixty-four data bits in parallel in a clockcycle, and the system can also include four modules 906 such as thecomponent 1000 described with reference to FIG. 9, each module 906configured to transfer sixteen data bits in parallel in a clock cycle(i.e., each module 906 can include two sets of first and secondmicroelectronic elements, each of the four microelectronic elementsbeing configured to transfer four data bits in parallel in a clockcycle).

In the example depicted in FIG. 9, the component 908 is a semiconductorchip and component 910 is a display screen, but any other components canbe used in the system 900. Of course, although only two additionalcomponents 908 and 910 are depicted in FIG. 9 for clarity ofillustration, the system 900 can include any number of such components.

Modules or components 906 and components 908 and 910 can be mounted in acommon housing 901, schematically depicted in broken lines, and can beelectrically interconnected with one another as necessary to form thedesired circuit. The housing 901 is depicted as a portable housing ofthe type usable, for example, in a cellular telephone or personaldigital assistant, and screen 910 can be exposed at the surface of thehousing. In embodiments where a structure 906 includes a light-sensitiveelement such as an imaging chip, a lens 911 or other optical device alsocan be provided for routing light to the structure. Again, thesimplified system shown in FIG. 9 is merely exemplary; other systems,including systems commonly regarded as fixed structures, such as desktopcomputers, routers and the like can be made using the structuresdiscussed above.

In any or all of the microelectronic packages described in theforegoing, the rear surface of one or more of the microelectronicelements can be at least partially exposed at an exterior surface of themicroelectronic package after completing fabrication. Thus, in themicroelectronic package 10 described above with respect to FIG. 1A, therear surface 32 of the microelectronic elements 30 can be partially orfully exposed at an exterior surface of an encapsulant in the completedmicroelectronic package 10.

In any of the embodiments described above, the microelectronic packagemay include a heat spreader partly or entirely made of any suitablethermally conductive material. Examples of suitable thermally conductivematerial include, but are not limited to, metal, graphite, thermallyconductive adhesives, e.g., thermally-conductive epoxy, a solder, or thelike, or a combination of such materials. In one example, the heatspreader can be a substantially continuous sheet of metal.

In one embodiment, the heat spreader can include a metallic layerdisposed adjacent to one or more of the microelectronic elements. Themetallic layer may be exposed at the rear surface of the microelectronicelement. Alternatively, the heat spreader can include an overmold or anencapsulant covering at least the rear surface of the microelectronicelement. In one example, the heat spreader can be in thermalcommunication with at least one of the front surface and rear surface ofeach of the microelectronic elements such as the lower and/or uppermicroelectronic elements 530 a, 530 b shown in FIGS. 5A and 5B. The heatspreader can extend between adjacent edges of adjacent ones of themicroelectronic elements. The heat spreader can improve heat dissipationto the surrounding environment.

In a particular embodiment, a pre-formed heat spreader made of metal orother thermally conductive material may be attached to or disposed onthe rear surface of one or more of the microelectronic elements with athermally conductive material such as thermally conductive adhesive orthermally conductive grease. The adhesive, if present, can be acompliant material that permits relative movement between the heatspreader and the microelectronic element to which it is attached, forexample, to accommodate differential thermal expansion between thecompliantly attached elements. The heat spreader may be a monolithicstructure. Alternatively, the heat spreader may include multiplespreader portions spaced apart from one another. In a particularembodiment, the heat spreader may be or include a layer of solder joineddirectly to at least a portion of a rear surface of one or more ofmicroelectronic elements such as the lower and/or upper microelectronicelements 530 a, 530 b shown in FIGS. 5A and 5B.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

It will be appreciated that the various dependent claims and thefeatures set forth therein can be combined in different ways thanpresented in the initial claims. It will also be appreciated that thefeatures described in connection with individual embodiments may beshared with others of the described embodiments.

1. A microelectronic package, comprising: a substrate having first andsecond opposed surfaces; at least two pairs of microelectronic elements,each pair of microelectronic elements including an upper microelectronicelement and a lower microelectronic element, the pairs ofmicroelectronic elements being fully spaced apart from one another in ahorizontal direction parallel to the first surface of the substrate,each lower microelectronic element having a front surface facing thefirst surface of the substrate and a plurality of contacts at the frontsurface, the front surfaces of the lower microelectronic elements beingarranged in a single plane parallel to the first surface, a surface ofeach of the upper microelectronic elements at least partially overlyinga rear surface of the lower microelectronic element in its pair, themicroelectronic elements together configured to predominantly providememory storage array function; a plurality of terminals exposed at thesecond surface, the terminals configured for connecting themicroelectronic package to at least one component external to themicroelectronic package; and electrical connections extending from atleast some of the contacts of each lower microelectronic element to atleast some of the terminals.